The invention relates to electrical probes useful for the testing and measurement of electrical circuit devices under test. In particular, the invention relates to a single point, differential structure and method for the testing of devices under test for electrical circuits.
In the testing of electrical devices, a single point probe, commonly known as the flying lead, is used to measure a single signal. Often, rather than simply measuring a single signal, however, it is necessary to measure the difference between two signals. A differential probe is capable of measuring the difference between two signals and may be used to measure signals not referenced to a ground, signals with a common interference signal or signals with large dc offsets.
Adaptation of a single flying lead probe as a differential probe poses some difficulty. Two flying leads, rather than one, are required and the spacing of their terminations away from the contact area can introduce unwanted parasitic electrical effects, particularly when measuring fasts signals, that have an adverse impact on accurate signal measurement.
The probe of the invention includes a termination network operable to minimize reflections between the probe measuring structure and the signals being measured at the device under test. The termination network may reside at the probe structure itself or be located at the device under test in a termination network connector coupled to the device under test. The termination network connector may be a solder-down connector soldered to an electrical device under test at a selected point. The solder-down connector may include a termination network, to minimize reflections, and connection pins for two signals and, optionally, a ground connection for non-differential operation. The probe head includes connection sockets that may be attached to the pins of the solder-down connector to connect it to an analyzer or other measurement device. The solder-down connector may be attached via solder pads on the electrical device under test to one or more of the target signal lines to permit differential measurements.